The angel’s share refers to the portion of whiskey (or other spirits) that evaporates from oak barrels during the aging process. As whiskey matures in casks, a small percentage of the liquid escapes through the pores of the wood into the atmosphere, typically amounting to about 2–5% of the volume per year, depending on factors like the climate and storage conditions.
This phenomenon occurs because oak barrels are slightly porous, allowing air to interact with the whiskey inside. While this interaction improves the whiskey’s flavor and character, the loss to evaporation is inevitable. The term “angel’s share” is a romantic expression coined to suggest that the lost whiskey is taken by angels, lending a poetic charm to what would otherwise be considered a financial loss.
Factors Influencing the Angel’s Share:
Climate: In warm climates, evaporation tends to be higher due to increased heat and humidity.
In cooler climates, the rate is slower, but aging takes longer.
Barrel Type: Smaller barrels have a larger surface area relative to their volume, leading to more evaporation.
Warehouse Environment: Humidity levels affect whether more alcohol or water evaporates. In dry climates, water loss predominates, increasing the whiskey’s alcohol concentration, while in humid climates, alcohol evaporates more readily.
Duration of Aging: The longer whiskey ages, the more is lost to the angel’s share, which is why older whiskeys are rarer and more expensive.
Despite the loss, the angel’s share plays a crucial role in the whiskey’s development, as it allows the spirit to “breathe,” contributing to its depth, smoothness, and complexity.